My experience with LP's may be of interest. I recently bought a Graham Slee Revelation and Elevator phono preamp. The Revelation (the upscale version of the Jazz Club) has variable equalization for vinyl. It has three switches with three positions each to recreate RIAA and several other EQ's including the old ffrr Decca and Columbia and various 78 rpm. I reported on the Oistrakh (TP-006), that the vinyl matches the tape in tone quality only with the ffrr Decca EQ. There is a hugh difference in playing back old EMI and Decca recordings with the proper EQ. I am getting a lot of enjoyment, particularly with the early EMI's which had previously been not pleasant to listen to. The Decca's are also much improved. I'm not sure where the EQ issue occurs. It seems from the Oistrakh tape that the masters are fine, but that in cutting the vinyl, the EQ is put in. I'm not sure when the standardization to RIAA occurred for each of the companies, but later (late 60's and 70's) issues seem fine with RIAA and late 50's and early 60's need the different EQ. For those with regular and low output MC cartridges, the Graham Slee Elevator boosts the gain by 20db and also has adjustable loading which feeds into the Revelation. The total package is aboiut $2500, less than many high end phono preamps. HiFi+ January 2008 issue talks about this.
Larry